Are you sure the battery has enough juice (13.5volts)? Is the engine locked up? Try turning the motor by hand. If the engine is not seized, take the starter off and bench test it. Recheck your negative battery cable, a very good chance your problem lies there.
The same thing happened to my 1995 full size bronco today. I took the battery cables off cleaned each one, and still the same problem. I replaced the starter, solenoid, finally noticed my ground wire from my intake to the fire wall was charred. So I checked my lower battery cable connections and my ground was not connected. I replaced my firewall ground and replaced my battery ground wire and all my problems were solved. Even my dash readings were fixed, I always had crazy readings on my dash (temp, oil pressure and amp gauge) all were fixed with the installation of my new ground wires.
It could be poor battery connections, the starter,
You should locate and test the solenoid. Most have three connections. There is a large cable from the battery to the solenoid, from the solenoid to the starter and from the start switch to the solenoid. The power terminals to the battery and the starter are large and have large cables. The starter switch connection is much smaller. Turning the key to 'start' provides a low current voltage to the solenoid causing the solenoid relay to close and power from the battery cable to connect through to the starter. If that voltage is present then the solenoid or the wiring between the solenoid and battery or solenoid and starter is suspect. If that voltage is missing then the starter switch or solenoid feed line may have failed.
This wire is connected to the solenoid along with a wire going to the power distribution system (Fuse box), but the connection or split is after the fusible link on the wire comming from the alternator. On most vehicles, those connections are attached to the same solenoid bolt. The connection there at the bolt, is done there because the large Positive battery cable also comes to that bolt.
The problem can be that the battery terminals are not tight enough or that the battery cables are worn out. A starter needs really tight contact to the battery in order to supply enough current to the solenoid and starter -- merely touching the terminals won't be enough.
The O2 (Oxygen Sensor) has nothing to do with the engine not starting. If it will not start you either have no spark or no fuel. If the engine will not turn over, it is either the starter, battery, connections, ignition switch, or starter solenoid. Some starters have the solenoid built into the starter. Test the battery, and all connections. Remove the starter and have it tested at any auto parts store.
It could be poor battery connections, the starter,
Battery is dead or you have a bad solenoid. Connections at the solenoid and/or starter could be loose or corroded.
Look for loose connections at the battery, starter solenoid, starter and switch. If all connections are good, the starter solenoid probably needs to be replaced.
Many times its corroded battery terminals, Pop off and clean it. Make sure the battery terminals are tight. Check for loose connections on black wire to frame and the connection to the starter. Have the battery tested as it may be getting weak (free at most part stores). If the above fails, replace it. Normally the solenoid is part of the starter and not sold separately.
Check for a bad fusable link at alternator
Try an ignition switch.
Starter Ignition Neutral switch
It could be solenoid, starter, battery, alternator not CHARGING the battery or corroded battery terminals.
solenoid is bad ,have it replaced,but check for remote solenoid first some vehicles have another solenoid mounted closer to battery
You should locate and test the solenoid. Most have three connections. There is a large cable from the battery to the solenoid, from the solenoid to the starter and from the start switch to the solenoid. The power terminals to the battery and the starter are large and have large cables. The starter switch connection is much smaller. Turning the key to 'start' provides a low current voltage to the solenoid causing the solenoid relay to close and power from the battery cable to connect through to the starter. If that voltage is present then the solenoid or the wiring between the solenoid and battery or solenoid and starter is suspect. If that voltage is missing then the starter switch or solenoid feed line may have failed.
I have the exact same pproblem with a 1988 tempo, replaced the alternator and battery, still the alternator only reads 5 volts when running. Can't figure it out, do you know of any websites that would have a diagram of the alternator for a tempo?
battery hooked up backward, wires crossed somewhere or it could be the solenoid.